Two-stroke internal-combustion engine



May 29 1951 Y J. E. sERs'rE ETAL 2,554,645

TWO-STROKE INTERNAL-COMBUSTION' ENGINE i Filed oor. s1, 1949 4shees-sheet 1 A A f, A t {Inf/0 'f ifi/1111411111111,

AT EY.

J. E. sERs'r ET Al.

Two-STROKE 1NTERNALC0MBUSTI0N ENGINE May 29, 1951 i Filed Oct. 5l, 19494 Sheets-Sheet 2 u .f A l I Q anniv/J m. ...x A

AT TORNEY.

.L A T E T S R E S E lum TWO-STROKE INTERNAL-COMBUSTION ENGINE 4Sheets-'Sheet 5 Filed 001.. 31, 1949 AT1-oww 29, 1951 J. E. SERS-rE: ETAL 2,554,645

TWO-STROKE INTERNAL'-CONIBUSTIOIl ENGINE Filed Oct. 3l, 1949 4Sheets-Sheet 4 Patented May 29, 1951 TWO-STROKE INTERNAL-COMBUSTIONENGINE Jacques Egde Serst, Jacqueline Serst Teplow, Paul Serst, andPierre Sei-st, Forest-Brussels,

Belgium Application October 31, 1949, SerialNo. 124,524 In theNetherlands October 25, 1948 19 Claims. 1

Our invention has for its object internal combustion and the likeengines of the two stroke type, the scavenging and the movements of theload being executed under equicurrent conditions throughout thecylinder.

In two stroke engines of standard type, the illling of the cylinders isobtained by loading them through a stream of fresh gases blown into samefor exhausting the burnt gases. It is thus necessary to incorporate apumping system so as to suck in the fresh gases and to deliver them intothe cylinder inside which they unavoidably come into contact with theresidual gases that have already expanded through their laminatingpassage inside the exhaust ports under delivery pressure while in closecontact with the fresh gases. Said contact between two gases, even of avery short duration, can but stir the masses with one another, whichleads on one hand to losses of fresh gases exhausted with the burntgases and on the other hand to a sort of poisoning of the load throughthe burnt gases'admixed therewith.

The suction and exhaust means provided for such conventional engines donot allow contemplating any other solution to the problem.

O ur invention has for its object to bring a deep modication to thestandard technique, the movements of the load being assured through anextremely rapid opening and closing of the large sized suction andexhaust ports so as to provide an immediate exhaust of the residuarygases at one end of the cylinder under the action of their spontaneousexpansion. By reas-on of their dynamic energy the mass of exhaustedgases sucks in energetically the gases forming the load through thesuction ports that have been uncovered in the meantime at the other endof the cylinder. The rapid closing of the exhaust ports stops then thepassage of this current of gases arriving at full speed and causes thelatter to settle over a height corresponding to the volume and speed ofsaid current while the closing of the suction ports opposes theretrogression vlof the,

gases and produces an excess pressure inside the cylinder. The overloadincreases by reason of the acceleration of the engine speed and mayreach considerable values.

Whereas in engines of the fuel injectiontype, the adjustment .allows anexcess passageof air,

the case is not the same in engines where the explosive load issubmitted to a preliminary stirring and cannot be lost. In this lattercase, the adjustment may loe-executed in a manner such that the burntgases and the load move with an intermediary zone of depression betweenthem that i's cut in vacuo through a closing of the exhaust whichremoves the possibility of a loss of rich gases without changing theconditions of admission and delivery for the engine.

We have shown by way of example and by no means in a binding sense,various embodiments of our invention. In said drawings:

Fig..l is a sectional view of yan engine incorporating the principle ofour invention.

Fig, 2 illustrates a modication thereof.

Fig. 3 shows on `a larger scale and cross sectionally the upper part ofan engine with an overhead valve gear.

Fig. 4 is a graph showing the transmission-gear for every 10 of therevolution of the eccentric.

Fig. 5 is a graph giving out the movements of the driving piston forevery 10 of said revolution.

Fig. 6 is a diagram corresponding to the graphs of Figs. 4 and 5 for twodiiierent adjustments.

Fig. 7 illustrates a set of control links operating in the same plane.

Figs. 8 and 9 illustrate modifications of this arrangement of controllinks.

Fig. 10 is an elevational view of a cylinder sleeve with two slidevalves controlled by a compensation bar.

Fig. 11 is a diagrammatic showing of the control means for a radialengine.

Figs. 12 and 13 are diagrammatic illustrations in side and elevationalviews of the control mechanism driven by a crankshaft provided with twosleeves and with further links.

Fig. 14 is an elevational view of a cam-operated control system.

In the embodiment illustrated in Fig. 1 the engine includes primarily-anengine unit I `with its crankcase 2, its water jacket 3,v its exhaustpipe 4its admission pipe 5 and its head 6 engaging the cylinder down tothe upper level of the upper ports provided for the passage of thegases.

The crankshaft 'l and its connecting rod 8 are operatively( connectedwith the piston 9 slidably carried inside Vthe stationary sleeve I0.Said sleeve is provided with upper ports II and with lower ports I2which latter are in register with a point occupied by a point of thehead of the driving piston just above the lower dead center of thepiston stroke.

The sleeve I is enclosed by the slide valve I3 the ports Ill and I inwhich are adapted to move respectively over the ports EI and over theports I2 in the sleeve under the action of a mechanism oprated by aneccentric I6 driven by the engine and including a link connection I'l--Ibetween said eccentric and the slide valve, said link connectionpivoting round the spindle axist I9. The transmission of the slidingmovement to the slide valve I3 for covering and uncovering the ports IIand I2 is obtained through cooperation with the link 2t controlling saidslide valve in either direction, the direction of the movement of theslide valve being always opposed to that of the driving piston.

The rst slide valve I3 is enclosed inside a further slide valve 2|provided with ports 22 crossing the ports I for registering at apredetermined moment of their movement with the ports II andsimultaneously with the ports I4, the movement of said slide valve 2|being controlled by a bar 23 connected with both slide valves I3 and 2|for providing their movements in opposite directions. These opposedmovements are obtained through the rods 24 and 25 while the head of thepiston 9 moves in a direction opposed to that of the ports I5 in theslide valve I3 so as to uncover the admission ports I2 in cooperationwith the latter ports.

This arrangement of two slide valves moving simultaneously in oppositedirections provides openings of the same size as a single slide valvebut it produces their covering and uncovering in half the time requiredwith a single slide valve operating with equal lengths of stroke ineither direction, while allowing the possibility of providing thedesired shifting for the timing and duration of exhaust and admission.

Referring to Fig. 2, it is apparent that it is similar to Fig l with thedifference that the slide valves I3 and 2| are housed inside the enginecylinder, the slide valve I3 taking the place of the cylinder lining Ii)and serving as a bearing for the driving piston 9 without anything beingchanged in the closing operation performed by it. Furthermore the slidevalve 2| is controlled by a projection controlled in its turn by a rod21 while the connections disclosed hereinabove as provided between theslide valves I3 and 2l are cut out as illustrated.

As illustrated in Fig. 3, the timing gear is carried in overheadrelationship with the engine so as to locate next to it, the compactarrangement of Fig. l including the eccentric IB, a pivoting link systemI'I-I8 connected with the stationary\pivot i9 and the link 25 acting onthe compensating bar 23 for transmitting the movement to the slide valve2l and to the slide valve I3 through the agency of the correspondingrods 25 and 24.

The operation of the three embodiments will appear in the graphs ofFigs. 4 and 5 and in diagram of Fig. 6. Thus Fig. 4 shows for each 10 ofthe revolution of the eccentric IB the location of the mechanical systemand chiey of the compensating bar provided for the control of the slidevalves.

Fig. 5 illustrates for every 10 of the movement the location of thedriving piston for the portion of the stroke thereof corresponding tothe covering and uncovering of the lower ports.

Fig. 6 is a diagram illustrating clearly the practical consequences ofthe graphs of Figs. 4 and 5 with two different timings of the opening ofthe exhaust through the upper ports, and of the admission through thelower ports; the curves show the movements in opposite directions of thecooperating moving ports.

The timing of the admission through the lower ports corresponds to thedrawing in solid lines while the other timing with admission through theupper ports and exhaust through the lower ports corresponds to thedrawing in dot and dash lines. The reference numbers given are the sameas those of the ports in the stationary sleeve I oi Fig. l while thehatched parts IIL-I23 correspond to the capacities of the exhaust and.the hatched parts E22 and I I3 correspond to the capacities of theadmission, the engine being supposed to have its exhaust built inoverhead relationship.

Within the scope of the invention, it is possible for instance to cutout the slide valve 2I and the transmission means controlling it in anyof Figs. 1, 2 and 3 so as to provide a single covering means for theupper ports while the lower ports remain controlled by double coveringmeans of which one is actually formed by the moving piston.

it is possible also for the driving piston to provide alone for thecontrol of the lower ports while one or two covering members or slidevalves control the upper ports.

rEhese various combinations are applicable with advantages that aresimilar to those provided by the embodiments illustrated, chiefly in thecase of engines with small or average sized cylinder capacities inaccordance with the cycle of operations disclosed by the diagrams.

Fig. '7 illustrates on a larger scale and in plan view a system of linksof the type illustrated in Fig. l together with their controlling andconnecting means operating in a same plane.

Figs. 8 and 9 illustrate a combination of the f system of links andcontrol means operating in several planes for actuating two slide valvesmoving in opposite directions as in the case of Figs. 2 and 3.

Fig. l0 shows a cylinder sleeve I D provided with two slide valves I3and 2| attached respectively at I3 and at 2|. Said points I3 and 2l areconnect d through rods 2@ and 25 to two projections deilning acompensator bar 23, which projections are secured to the rocking shaftI9 controlled by a set of links not illustrated.

In Fig. ll, we have illustrated a control system for an engine thecylinders of which are arranged in radial relationship while thedifferent slide valves are actuated by a common eccentric I6 secured toa shaft 3? forming an extension of the crankshaft, the link system ofeach cylinder being pivotally secured to a ring 3i controlled by theeccentric i6 and held in a stable position through the eccentric 53connected with the projection :i2 on said ring 3l. It is thus apparentfrom inspection of Fig. l1 how the position oi the links lies for theseven stages of a cycle extending a little over 51 of the revolution ofthe crankshaft.

This arrangement is applicable as well of course to all engines with aradial sectional arrangement.

A control mechanism for the slide valve or valves includes furthermembers with the object either of shifting the moments of accelerationor assailant of -adjusting the magnitudes governing the 'strokes andaccelerations or else of obtaining any other modication in accordancewith the re- ,quirementsof the cycle of operation or the constitution ofthe engine. This is shown in Figs. .l2 and 13 where the crankshaft isprovided with asecond crank of eccentric-33 acting on the connectingrods Sil, 35 of which the latter is inserted between'the connection withthe links Il, i8 and the connecting rod Z leading to the slide valves.

Turning to Fig. 14 said figures show a camoperated control mechanismensuring a positive drive in both directions.

To the shaft 36 are secured in different planes cams 3l and 38 ci whichthe -former engages the roller Se while the second cam engages theroller lill. The two rollers are rotatably carried by the compensatormember' 23 through 'the agency of a rocking shaft 35 controlling theslide valves I3 and 2| knot illustrated through the connectionsVprovided by the rods 2d and 25.

During the period during which the rollers 39 and dtlfare in contactwith parts of the cams .3l and 33 co-a-Xial with the shaft 35, themovement of the slide valves is zero, said movement being startedsuddenly through eccentric portions of said cams. The whole cycle ofoperation of the cams is executed without either of them movingtheoretically out of contact with reference to its rollers. covering ofthe ports similar to that appearing in Fig. 6.

From the preceding disclosure, it is apparent that the port coveringmember operating Asingly controls the corresponding ports at a speedthat may be suiiicient lfor operation with either rate of operation ofthe ports, while retaining all the advantages described Vfor certaincategories of vengines-whereas for other categories, it is necessary toresort to double covering members because they may double the speed ofcovering and of uncovering the passages for the gases.

Without unduly widening the scope of the invention as defined inVaccompanying claims,.it is possible to incorporate the abovearrangement of y slide valves and of a piston to double acting enginesor the like, both for exhaust .and for admission and the shifting of thetiming may be obtained without any shifting of the relationship betweenthe crankp-ins of the two driving crankshafts to be considered; themovement of the closing slide valves mai7 be operated axially of thecylinder or else itis possible to make them assume a tacking movementwith reference to said cylinder.

This arrangement may'lead to an unl The arrangement disclosed is alsoapplicable for other arrangements of the cylinders with .an engine ofradial or radial section type, also `with engines of the double ormultiple actingtype or else having moving cylinders arranged in squareor the like formation. The connections between the control means and theslide valves may `be performed also through the head of yeach cylinder;any further arrangements of links and transmission means and relays maybe inserted between the control means and the slide valves; the slidevalves may be constituted by interconnected sections or else thesesections may be controlled by a crankshaft provided with a plurality Aofcranks or by a plurality of crankshafts; the control and transmissionmeans may be secured to a number of stationary points and in brief anycombination may be made between the elements described and disclosed.

Obviously, our invention has been describedas 6 illustrated by way of a.mere indication and `by no means in a limiting ysense and numerousmodications may be brought to the details thereof withoutl undulyWidening thereby the scope offtl'ie invention as defined in accompanyingclaims.

What We claim is:

1. In a two stroke internal combustionand the like engine, thecombination of a cylinder provided at each end with two series of portsadapted respectively to serve as admission portsand asexhaust ports,'the upper series of ports being provided .at the upper end of thecylinder and the lower series opening substantially at the lower end ofthe combustion chamber in the cylinder, a driving piston adapted toreciprocate inside the cylinder between an upper dead point and a lowerdead point substantially in register with the lower series oi ports, aslide valve slidably engaging onel of the surfaces of the cylinder landprovided with a series of ports adapted to register with the upperseries of ports in the cylinder, a linlrwork connected with the slideValve for producing a sliding movement of the latter over'thecooperating surface of the cylinder, an eccentrically operating membercontrolling the link work to constrain the slide valve to operatecyclically, the cyclic operation of the valve including a long period ofvery small oscillations providing for the covering of the upper seriesof ports in the cylinder and then a very highly accelerated movementvfor uncovering and then covering again said upper seriesof ports in thecylinder while the valve moves at high speed and produces thus anopening of the upper ports with a large cross-sectional passage during avery short time, the cycle terminating with the return into the portcovering position, the driving' piston being adapted to cover anduncover the lower series of ports in the cylinder a lag being providedbetween the uncovering of the upper series of ports and that of thelower series of ports in the cylinder.

2. In a two stroke internal combustion and the `like engine, thecombination of a cylinder provided at each end with two series of portsadapted respectively to serve as admission ports and as exhaust ports,the upper series of ports being provided at the upper end of thecylinder and the lower series opening substantially at the lower end ofthe combustion chamber in the cylinder, a driving piston adapted toreciprocate inside the cylinder between an upper dead point and a lowerdead point substantially in register with the 10W- er series of ports,a. slide valve provided with two series of ports adapted to registerrespectively `with the upper and with the lower series of ports in thecylinder, a linkwork connected with the slide valve for producing asliding movement of the latter over the cooperating surface of thecylinder, an eccentrically operating member con'- trolling the linkworkto constrain the slide valve to operate cyclically, the cyclic operationof the valve including a long period of very small oscillationsproviding for -the covering `of the upper and lower series of ports inthe cylinder and then a very highly acceleratedmovement for uncoveringYand then covering again said upper and lower series of ports in thecylinder while the valve moves at a high speed and produces thus anopening of the upper porls with a large crosssectional passage during avery short time, vthe cycleterminating with the return into the portcovering position, the driving'piston cooperating with the lower seriesof ports in the slide valve for uncovering and covering at a high speedsaid lower series of ports in the cylinder through a movement that issimultaneous with and in the opposite direction with reference to thatof the slide valve in front of said lower series of' ports, a lag beingprovided between the uncovering of the upper series of ports and that ofthe lower series of ports in the cylinder.

3. In a two stroke internal combustion and the like engine, thecombination of a cylinder provided at each end with two series of .portsadapted respectively to serve as admission ports and as exhaust ports,the upper series of ports being provided at the upper end of thecylinder .and the `lower series opening substantially at the lower endof the combustion chamber in the cylinder, a driving piston adapted toreciprocate inside the cylinder between an upper dead point and a lowerdead point substantially in register with the lower series of ports, twoslide valves provided each with a series of ports adapted to registerwith the upper series of ports of the cylinder, said slide valves beingarranged to either side of the cylinder wall and being adapted to movesimultaneously and in opposite directions in register with the upperports in the cylinder for covering and uncovering same through theircooperation, a linkage connected with at least one slide valve, aneccentric member positively controlling said linkage, a rocking leveroperatively connecting the two slide valves together, said arrangementof the linkage, eccentric and rocking lever being adapted to constrainthe slide valves to move in opposite directions when closing the upperseries of ports in the cylinder and to operate cyclically, the cycle ofoperation including a long period of short oscillations while the .slidevalve closes the upper series of ports in the cylinder, after which theslide valves assume a high acceleration for uncovering and then coveringagain said upper series of ports in the cylinder while the valves moveat high speed and produce thus an opening of the upper ports with alarge cross-sectional passage during a very short time, the cycleterminating with the return into the port covering position, the drivingpiston being adapted to cover and uncover the lower series of ports inthe cylinder, a lag being provided between the uncovering of the upperseries of ports and that of the lower series of ports in the cylinder.

4. In a two stroke internal combustion and the like engine, thecombination of a cylinder provided at each end with two series of portsadapted respectively to serve as admission ports and as exhaust ports,the upper series of ports being provided at the upper end of thecylinder and the lower series opening substantially at the lower end ofthe combustion chamber in the cylinder, a driving piston adapted toreciprocate inside the cylinder between an upper dead point and a lowerdead point substantially in register with the lower series of ports, twoslide Valves provided each with a series of ports adapted to registerwith the upper series of ports of the cylinder, said slide valves lyingrespectively in contact with one surface of the cylinder and with thesurface of the iirst slide valve that is not in contact with thecylinder wall and being adapted to move simultaneously and in oppositedirections in register with the upper ports in the cylinder for coveringand uncovering same through their cooperation, a linkage connected withboth slide valves, an .eccentric controlling said linkage forconstraining the slide valves to move in opposite directions whenclosing the upper series of ports in the cylinder and to operatecyclically, the cycle of operation including a long period of shortoscillations while the slide valve closes the upper series of ports inthe cylinder, after which the slide valves assume a high accelerationfor uncovering and then covering again said upper series of ports in thecylinder while the valve moves at high speed and produces thus anopening of the upper ports with a large crosssectional passage during avery short time, the cycle terminating with the return into the portcovering position, the driving piston being adapted to cover and uncoverthe lower series of ports in the cylinder, a lag being provided betweenthe uncovering of the upper series of ports and that of the lower seriesof ports in the cylinder.

5. In a two stroke internal combustion and the like engine, thecombination of a cylinder providedv at each end with two series of portsadapted respectively to serve as admission ports and as exhaust ports,the upper series of ports being provided at the upper end of thecylinder and the lower series opening substantially at the lower end ofthe combustion chamber in the cylinder, a driving piston adapted toreciprocate inside the cylinder between an upper dead point and a lowerdead point substantially in register with the lower series of ports, twoslide valves of which one is provided with two series of ports adaptedto register respectively with the upper ports of the cylinder and withthe lower series of ports while the other slide valve is provided with asingle series of ports adapted to register with the upper series ofports of the cylinder, at least one of said slide valves lying incontacting relationship with one of the surfaces of the cylinder, alinkage connected with at least one slide valve, means associated withthe linkage for constraining the two slide valves to move in oppositedirections and to register simultaneously through their upper ports withthe upper series of ports in the cylinder for covering and uncoveringsame, the cycle of operation of the slide valves including acomparatively long period of small oscillations during which the upperand lower series of ports in the cylinder are closed, following which ahigh acceleration leads to the uncovering and covering at a high speedof the upper series of ports in the cylinder through simultaneousregistering thereof with the upper ports in both slide valves to providea high speed opening with a large throughput area for said ports, afterwhich the upper and lower series of ports in the cylinder are coveredagain, the piston cooperating with the first slide valve for controllingthe lower ports in the cylinder for uncovering and covering same througha movement of the piston that is simultaneous with and in oppositedirection with reference to the lower series of ports in the rst slidevalve, a shifting in time being provided between the uncovering of theupper and of the lower series of ports in the cylinder.

6. In an engine of the two stroke internal combustion type, thecombination of at least one cylinder provided in its wal1 with anannular series of ports at either of its ends, a gas feeding pipecommunicating with one series of ports at the upper end of the cylinder,a gas feeding pipe opening into the other series of ports at the lowerend of the cylinder, a driving piston adapted to reciprocate inside thecylinder and to uncover in its downward stroke, the ports correspondingto the lower cylinder, a slide valve provided with two annular series ofports adapted to register respectively with one series of ports in thecylinder wall, a further slide valve coaxial with the 1'irst slide valveand provided with ports registering with the upper ports in the cylinderwall and at the same time with the corresponding ports in the rst slidevalve for a predetermined position of said slide valve and meanscontrolling simultaneously the movement of the second slide Valve in thesame direction as the piston and that of the rst slide valve in theopposite direction with a shifting in time between the simultaneousuncovering of the upper ports by the corresponding ports of the twoslide valves and that of the lower ports by the piston and second slidevalve.

'7. In an engine of the two stroke internal combustion type, theco-mbination of at least one cylinder provided in its wall with anannular series of ports at either of its ends, a gas feeding pipecommunicating with the upper seriesof ports, a gas feeding pipe openinginto the lower series of ports, a piston adapted to reciprocate insidethe cylinder and to uncover at the end of its downward stroke, the portscorresponding to the second pipe,` at least one slide valve providedwith an annular series of ports and adapted to slide over the cylinderwall into and out of a position for which its ports register with apredetermined series of ports in the cylinder wall, means controllingsaid slide valve including an eccentric operatively connected with thepiston and a link system connecting said eccentric permanently with theslide valve for causing it to sweep past the corresponding series ofports in the cylinder wall at a speed that is high between the momentsof uncovering and of covering said cylinder ports while slowing down themovement of said slide valve during the periods during which the seriesof ports considered are out of register.

S. In an engine of the two stroke internal combustion type, thecombination of at least one cylinder provided in its wall with anannular series of ports at either of its ends, a pipe communicating withthe upper series of ports, a pipe opening into the lower series ofports, a piston adapted to reciprocate inside the cylinder and touncover at the end of its downward stroke, the ports corresponding tothe second pipe, at least one slide valve provided with at least oneannular series of ports adapted to slide over at least one cylinder wallinto and out of a position for which its ports register with apredetermined l series of ports in the cylinder wall, means controllingsaid slide valve including a cam system operatively connected with thepiston and a positively operated linkage between said cam system and theslide valves for causing them to sweep past at least one correspondingseries of ports in the cylinder wall at a full speed between the momentsof uncovering and of covering said cylinder ports while slowing down themovement of said slide valves during the periods during which the seriesof ports considered are out of register.

9. In an engine of the two stroke internal combustion type, thecombination of at least one cylinder provided in its wall with anannular series of ports at either of its ends, a pipe communicating withthe upper series of ports, another pipe opening into the lower series ofports, a piston adapted to reciprocate inside the cylinder and touncover in its downward stroke the ports corresponding to the secondpipe, coaxial slide valves adapted to move over one cylinder wall andhaving an annular series of ports adapted to register at a predeterminedmoment of their movements with one another and with i6 the ports in thecylinder wall and means con-I trolling the movements of said slidevalves vin opposite directions, including Vat least one eccentricoperatively connected with the piston and means connecting the two slidevalves to move same in opposite directions and controlled positively bysaid cam system.

l0. In an engine 01" the two stroke internal combustion type, thecombination of at least one cylinder provided in its wall with anannular series of ports at either of its ends, a pipe com-4 municatingwith the upper series of ports, another pipe opening into the lowerseries of ports, a piston adapted to reciprocate inside the cylinder andto uncover in itsl downward stroke, the ports corresponding to thesecond pipe, coaxial slide valves adapted to move over the cylinder Walland having an annular series of ports adapted to register' at apredetermined moment of their movements with one another and with theports in the cylinder walls and means controlling the movements of saidslide valves in opposite directions including at least one eccentricoperatively connected with the. piston and a compensating` barlconnecting the two slide valves to move same in opposite directions andcontrolled positively by said cam system. i

l1. In an internal combustion engine, the combination of two coaxialslide valves deiining a cylindrical chamber and provided respectivelywith one and with two annular series of. ports, the first of which isadapted to register with that in the first slide valve, a piston adaptedto reciprocate inside said cylindrical chamber and to uncover at the endof its stroke the second annular series of ports in the second slidevalve and means mechanically interconnecting the piston with each of thetwo cylindrical members for constraining the latter to move in oppositedirections with reference to the piston so as to bring the ports in thefirst cylindrical member into register with the second series of portsin the second slide valve at a predetermined moment with reference tothe uncovering of the second series of ports in the second slide valveby the piston and two pipes communicating respectively with the rst twoseries of ports when registering with one another and with the lastseries of ports when uncovered by the piston.

12. In a two stroke engine, the combination of a cylinder wall providedat each end with an annular series of ports, two pipes openingrespectively into the corresponding series of ports, at least onecylindrical slide valve cooperating with said cylinder wall and of whichat least one lies in direct contacting relationship with said cylinderwall, and each slide valve being provided with at least one series ofports adapted to register with the corresponding ports in the otherslide valve and in the cylinder wall, a piston slidingly engaging thecylinder and valve system, mechanical means controlling positively theoper-` ation of the valves and means permanently and mechanicallyconnecting the piston with the said mechanical means to constrain theports in at least one slide valve to execute rst slight oscillationsduring a comparatively long time and then to move at a very highVelocity for uncovering and covering the registering ports during a veryshort time over a large area, the piston being adapted to cooperate inthe uncovering of the lower ports with a shifting in time between theuncovering and covering of the two series of ports.

13, In a two stroke engine, the combination of a cylinder wall providedat each end with an 1 l annular series of ports, two pipes openingrespectively into the corresponding series of ports, two cylindricalslide valves cooperating with said cylinder wall and lying respectivelyin contacting relationship with each side of the cylinder wall and eachslide valve being provided with at least one series of ports adapted toregister with the kcorresponding ports in the other slide valve and inthe cylinder wall, a piston slidingly engaging the cylinder and valvesystem, mechanical means controlling positively the operation of thevalves and means permanently and mechanically connecting the piston withthe said mechanical means to constrain the ports in the slide valves tomove at a very high velocity into and out of register with thecorresponding cylinder wall valves, the piston being adapted tocooperate in the uncovering of the lower ports with a shifting in timebetween the uncovering and covering of the two series of ports.

14. In a two stroke engine, the combination of a cylinder wall providedat each end with an annular series of ports, two pipes openingrespectively into the corresponding series of ports, two cylindricalslide valves cooperating with said cylinder wall and lying respectivelyfor the first slide valve in contacting relationship with the cylinderwall and for the second slide valve with the surface of the rst slidevalve that is not in contact With the cylinder wall, and each slidevalve being provided with at least one series of ports adapted toregister with the corresponding ports in the other slide valve and inthe cylinder wall, a piston slidingly engaging the cylinder and valvesystem, mechanical means controlling positively the operation of thevalves and means permanently and mechanically connecting the piston withthe said mechanical means to constrain the ports in the slide valves tomove at a very high velocity into and out of register with thecorresponding cylinder wall valves, the piston being adapted tocooperate in the uncovering of the lower ports with a shifting in timebetween the uncovering and covering of the two series of ports. '15. Ina two stroke engine, the combination of a cylinder wall provided at eachend with an annular series of ports, two pipes opening respectively intothe corresponding series of ports, at least one cylindrical slide valvecooperating with said cylinder wall and of which at least one lies indirect contacting relationship with said cylinder wall, and each slidevalve being provided with at least one series of ports adapted toregister with the corresponding ports in the other slide valve and inthe cylinder wall, a piston slidingly engaging the cylinder and valvesystem, mechanical means controlling positively the operation of thevalves and means permanently and mechanically connecting the piston withthe said mechanical means to constrain the upper ports of the two slidevalves to move simultaneously in opposite directions in front of theupper ports of the cylinder for covering and uncovering same at a highspeed, the piston being adapted to cooperate in the uncovering of thelower ports with a shifting in time between the uncovering and coveringof the two series of ports.

16. In a two stroke engine, the combination of a cylinder wall providedat each end with an annular series of ports, two pipes openingrespectively into the corresponding series of ports, two cylindricalslide valves cooperating with said cylinder wall and lying respectivelyin contacting relationship with each side of the cylinder wall, and eachslide valve being provided with at least one series of ports adapted toregister with the corresponding ports in the other slide valve and inthe cylinder wall, a piston slidingly engaging the cylinder and valvesystem, mechanical means controlling positively the operation of thevalves and means permanently and mechanically connecting the piston withthe said mechanical means to constrain the upper ports of the two slidevalves to move simultaneously in opposite directions in front of theupper ports of the cylinder for covering and uncovering same at a highspeed, the piston being adapted to cooperate in the uncovering of thelower ports with a shifting in time between the uncovering and coveringof the two series of ports.

17. In a two stroke engine, the combination of a cylinder wall providedat each end with an annular series of ports, two pipes opening into thecorresponding series of ports, two cylindrical slide valves cooperatingwith said cylinder wall and lying respectively for the rst slide valvein contacting relationship with the cylinder wall and for the secondslide valve with the surface of the iirst slide valve that is not incontact with the cylinder wall, and each slide valve being provided withat least one series of ports adapted to register with the correspondingports in the other slide valve and in the cylinder wall, a pistonslidingly engaging the cylinder and valve system, mechanical meanscontrolling positively the operation of the valves and means permanentlyand mechanically connecting the piston with the said mechanical means toconstrain the upper ports of the slide valves to move simultaneously inopposite directions in front of the upper ports of the cylinder forcovering and uncovering same at a high speed, the piston being adaptedto cooperate in the uncovering of the lower ports with a shifting intime between the uncovering and covering of the two series of ports. Y

18. In a two stroke engine, the combination of a cylinder wall providedat each end with an annular series of ports, two pipes opening into thecorresponding series of ports, two cylindrical slide valves cooperatingwith said cylinder wall and of which at least one lies in directcontacting relationship with said cylinder wall, and each slide valvebeing provided with at least one series of ports adapted to registerwith the corresponding ports in the other slide valve and in thecylinder wall, a piston slidingly engaging the cylinder and valvesystem, an eccentric controlling lpositively the operation of the valvesand means permanently and mechanically connecting the piston with thesaid eccentric to constrain the ports in the slide valve to move at avery high velocity into and out of register with the correspondingcylinder wall valves, the piston being adapted to cooperate in theuncovering of the lower ports with a shifting in timebetween theuncovering and covering of the two series of ports.

19. In a two stroke engine, the combination of a cylinder wall providedat each end with an annular series of ports, two pipes openingrespectively into the corresponding series of ports, two cylindricalslide valves cooperating with said cylinder wall and of which at leastone lies in direct contacting relationship with said cylinder wall, andeach slide valve being Aprovided with at least one series of portsadapted to register with the corresponding ports in the other slidevalve and in the cylinder wall, a piston slidingly engaging the cylinderand valve system, a cam JACQUES EGIDE sERsT. JACQUELINE ,sERsT TEPLOW.PAUL sERsTE.

PIERRE sERsT.

14 REFERENCES CITED The following references are of vrecord in the le ofthis patent:

UNITED STATES liATENTs Number 15 Number Name Date Peache Apr. 23, 1912Pringle May 25, 1915 Stokes July 1, 1919 Cage Aug. 2, 1921 Bischof Dec.3, 1935 Allyn Apr. 1, 1941 FOREIGN PATENTS Country Date France of 1939

